This invention relates to an adjustable sight for a firearm and, more particularly, to improvements in such sights which enable a shooter to accurately position with fingertip control the elevation of a rear sight over a range of predetermined elevations thereof.
In competitive pistol shooting, targets are presented to the shooter at various ranges to test the shooter's ability to hit the bull's-eye or X-ring of each target. Due to the differences in target distance it is necessary to adjust the angle of bullet trajectory by adjusting the inclination of the gun barrel before firing. Gun sighting devices have addressed this adjustment by introducing the capability to variously adjust the elevation of the rear sight in response to different target distances.
Sighting devices in use employ different means to adjust a rear sight leaf so as to correspondingly adjust the elevation of an attached rear sight. One such means in use employs a horizontally disposed cam member laterally placed across a sight rib so as to functionally engage elevation screws attached to an overlying sight leaf. The necessity to laterally align the elevation screws for engagement with the underlying cam limits the number and range of elevations available to the rear sight, as dictated by the width of the sight leaf itself. Also, a structural weakness to the leaf across the line of alignment is introduced which, in some cases, leads to a break in the sight leaf itself.
Another sight rib in use consists of a vertically disposed screw rotatable about its own axis, which raises or lowers the attached leaf and sight mounted thereto in a jackscrew type of manner. This particular configuration requires the shooter to count and record the number of screw turns thus, necessitating the shooter himself to keep careful track of the screw position, lending itself to critical inaccuracies in the sight adjustment. In such a device there is no positive control available to the shooter to instantly recall previously selected sight positions.
In both cases it is necessary to use a screwdriver, allen wrench or other similar tool to actuate the employed means which is relatively cumbersome, annoying and tends to distract the shooter's concentration from the firing situation at hand.